The invention concerns electronic alarm and safety devices for isolated houses, apartments, industrial buildings, areas to protect generally. A great number of systems and types of equipment exist for protection against intruders of all kinds, divided substantially into two main groups. The first uses visual and acoustic warnings to indicate the presence of unexpected persons at unexpected times inside or close to buildings that may be inhabited or used for offices, industry, warehouses or other purposes.
The second informs a watchman, provided with a monitor, of the presence of persons and objects at unexpected times and places.
The two categories can of course be associated to get the best results.
The second referred to above is obviously the safest as any intruder trying to gain entrance can be seen at once.
But this second category is necessarily limited to large buildings or to the more luxory types of housing in view of the high costs involved, both for purchasing the necessary apparatus and for installing it, as well as for the personnel needed to watch the screen on which the image would appear.
The first category gives good results at moderate prices but presents the serious drawback of simultaneously warning not only the occupiers of the place to be protected but also the intruder who then has time to get away and avoid capture.
In any case the cost of a really efficient warning system is usually beyond the financial means of the would-be user who therefore has to forgo protection even where existence of a high risk would make it necessary.
These latter cases must include those relating to periods, which may even be quite long, when the attention of a person or a family is centered on a video image, for example in some isolated habitation during the evening, and little notice is likely to be taken of unusual noises partly covered by the sound emitted by a television set.
Another typical case is that of an office in which staff closely watching a computer cannot pay much attention to unusual noises or movements that might proceed from or be associated with the activity of an intruder of some kind.
In most apartment blocks the main outer door may easily be opened at once at the request of a visitor who does not arouse suspicion. Having opened the main door or even one to an apartment, the user may suddenly find himself face to face with some ill-intentioned person who can then enter without difficulty.
The above invention deals almost entirely with most of the above problems mainly using equipment already in the home or office simply adding inexpensive and easily-installed accessories.
Subject of the invention is an electronic anti-intruder alarm and protection system for isolated houses, apartment blocks, businesses and others.
This system comprises:
one or more electronic transmitting units, here called remote units, with micro-telecameras placed at the entrances, and inside and outside the buildings to be guarded;
a receiving electronic unit, here called a local unit, connected to a television or computer screen or to a video recorder, or the like.
Whenever some presence, usually a person, crosses the space covered by the telecamera, each remote unit automatically transmits the person""s image to the local unit which transfers it to the screen or to the video-cassette of the video recorder.
This image replaces any that may be present on the screen or are being recorded.
In this way the image of an unwanted intruder can be viewed immediately and be recorded in real time.
As soon as some presence enters the range of action of the telecameras, these remote units at once send the image to the local unit.
Similarly, when someone rings the bell at the entry to a building or presses a street buzzer button and in so doing enters the range of action of the telecameras, the remote units transmit the image to the local unit. Having received the image from the remote units, the local unit automatically turns on the screen of a television set or of a computer, or turns on a video recorder or automatically comes onto such screens replacing what was there before or replacing what a recorder was recording.
The remote units show their connection, hereinafter called xe2x80x9cactive connectionxe2x80x9d, with the local unit by signalling a xe2x80x9ccarrier presencexe2x80x9d.
When a proximity sensor, associated to the telecameras, notes a presence, especially of a person, in its field of action, it transmits a warning signal, hereinafter called a xe2x80x9cwarning signalxe2x80x9d, to said local unit.
When said local unit receives both the signal of xe2x80x9cactive connectionxe2x80x9d and the xe2x80x9cwarning signalxe2x80x9d, it produces a signal, hereinafter called a xe2x80x9cstarting signalxe2x80x9d, that determines transmission of the image to the television or computer screen or to the video recorder.
The remote units can be fitted with a twilight sensor which, when environmental light falls below a certain level, works a switch to light up a lamp that illuminates the field of action of the telecameras.
This present electronic system is modular and built in sections, so that:
the remote and local units can be equipped only with the functions that are desired for each case according to needs and preferences;
one or more, and one or other, of the remote and local units can be connected, and transmission frequencies of the remote units can be automatically dealt with by a single local unit;
connection of remote units to the local electronic unit can be made by coaxial cable, radio frequency, conveyed waves on the local electricity network or other means.
Active connection between one or more remote units and the local unit, by a signal of carrier presence at the entrance, is only available periodically as, in the absence of the warning signal, the telecameras are turned on for only a few seconds with previously set and programmable switch-off and scanning times, a retriggable monostable circuit arranging to generate an ever-present signal of active connection if the carrier presence signal is not missing for more than the previously set scanning time.
The local unit comprises a control panel on which, through a Scart socket, the user can choose connection to the screen of a television set or of a computer or to a video recorder and the like and can operate the following functions:
remote unit selection,
exclusion of the twilight sensor on the unit selected,
transmission of the image from the remote unit to a television screen,
transmission of the image from the remote unit to a computer screen,
recording of the image transmitted from remote unit to video recorder can note, by means of visual and acoustic warning devices, the following signals:
remote unit turned off
warning signal from remote unit
twilight sensor turned off on remote unit
The user""s choice is translated into a TV/TVR signal that indicates connection with the monitor or with the video recorder.
In the case of connection to the monitor, the warning signal is converted to a suitable electric level transmitted to one pin of the Scart socket; in the case of connection to a VPS-equipped video recorder, the signal is converted into an electric signal specific for the recorder and, in the case of connection to a recorder without VPS, to a signal which reaches a contact placed between two pins on the Scart socket.
In the case of transmission by means of radio waves, the signal from a telecamera modulates, by an RF modulator, a radio-frequency carrier radiated by a small antenna, arriving from a tone generator circuit, there being a different one for each remote unit as it is linked to the cabled address in xe2x80x9cunit addressxe2x80x9d circuits.
The audio band of the modulator is used for transmission of a subaudio tone for signalling a presence, especially that of a person, within the field of action of the proximity sensor.
In the case of conveyed-wave transmissions, the signal from the telecameras is coded and sent to a line coupler that conveys it along the electricity network, prevents the network frequency, 50 Or 60 Hz for example, from reaching receiver or transmitter inputs at levels that can impede their operation, puts a signal into the electricity line at a sufficiently high level and at a frequency that can pass along the line, the signal transmitted being then decoded by a conveyed-wave receiver.
In the local unit a conveyed-wave generator can advantageously be placed to generate the signal, in which information about the input logic level can be coded, to be passed to the line coupler for entry into the local a.c. mains network while, in the remote unit, a conveyed-wave receiver is present to decode the signal transmitted at a frequency corresponding to the unit address where the receiver is placed.
Advantageously the local unit comprises acoustic and visual warning devices, preferably on the panel, that signal a presence in the telecamera""s field of of action so as to warn the user of this presence, unless it is in the neighbourhood of the monitor or unless the monitor is outside its range.
Preferably the remote units can be associated with inclusion or addition of ordinary street lamps, other lamps, lighting equipment, buzzer plates for bells and for street bells, other forms of utilization generally.
The invention offers evident advantages.
By adding accessories at a practically negligible cost compared with the effects obtainable and possible, an ordinary television set, or PC, or an ordinary video recorder can be used not only as a video street buzzer and the like but also as an efficient alarm system, especially when the user""s attention is engaged by a television programme or computer work, in which cases the automatic appearance on the screen of some intruder is superimposed over what the screen was showing at that moment, so preventing action by any such intruder wishing to benefit from the user""s attention being otherwise engaged.
The possibility of using ordinary street lamps, other lighting means, bell and street buzzer panels and the like as remote units, is decisive in being able to place telecameras for this purpose in suitable positions.
By means of a single local unit such as a TV set, computer and the like even a considerable number of remote units, placed at various points in buildings of any kind, situation and size, can be kept under control.
It is thus possible to protect buildings of all kinds and extension at a very low cost and, further, such protection implies all the advantages of video types of street buzzers, giving not only immediate warning of danger but also offering a useful view of any visitor asking for admittance at a street door or at that of a private house or apartment.
Characteristics and purposes of the invention will be made still clearer by the following examples of its execution illustrated by diagrammatically drawn figures.